Electron tube having annular envelope



Aug. 1, 1950 c. E. MURDOCK ELECTRON TUBE HAVING ANNULAR ENVELOPE Filed Dec. 26, 1947 z 1. z 9 9 5 v w fi 3 3 6 7 w 8 8 g INVENTOR. Clayl'on -E. Murdock BY Mai ATTORNEY Patented Aug. 1 1950 UNITED STATES PATENT OFFICE ELECTRON TUBE HAVING ANNULAR ENVELOPE Clayton E. Murdock, Millbrae, Calif., assignor to Eitel-McCullough, Inc., San Bruno, Calif., a corporation of California Application December 26, 1947, Serial No. 794,000

improved electrode terminal arrangement adaptable for use with high frequency linear circuits.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of my invention. It is to be understood that I do not limit myself to this disclosure of species of my invention as I may adopt variant embodiments thereof within the scope of the claims.

Referring to the drawing: Figure l is an axial sectional View of a tube embodying the improvements of my invention;

and

Figure 2 is a fragmentary sectional View showing a modified structure with a single grid terminal and an indirectly heated cathode.

In terms ofbroad inclusion my tube comprises an annular envelope having cylindrical inner and outer side walls, a plurality of ring-shaped electrodes, and ring-shaped electrode terminals on the envelope, the envelope side walls and electrodes and electrode terminals all being concentric with the tube axis. In a triode type of tube having an anode, grid and cathode, the anode preferablyforms a part of one side wall and a cathode terminal a part of the other side wall, the grid terminal being preferably located between the side walls at one end of the envelope.

preferred structure the metal anode 3 forms a part of the outer wall. Two ring-shaped cathode terminals l and 8 are provided on the envelope and are preferably arranged to form part of the inner wall of the envelope. These terminals are conveniently cylindrical metal sleeves disposed one within the other, the inner terminal I of which lies in the circle defined by the inner envelope wall. Two ring-shaped grid terminals Band H3 are also preferably provided on the envelope. These are coaxially aligned cylindrical metal sleeves and are located between the side walls at opposite ends of the envelope.

The vacuum-tight envelope is completedby several sections of insulating or vitreous material such as glass. Upper and lower end sections II and H! of annular U-shape complete the outer wall and are sealed along the outer edges to flanges it connected to the anode 3. Shields 14 on flanges l3 protect the seals against heat and electron bombardment. The inner edges of glass sections H and I2 are sealed to flanges IS on the grid terminals 9 and Ill. Another annular U-shaped section 16 at the upper end of the tube is sealed along one edge to a flange I! on the upper grid terminal 9 and along another edge to a flange [8 on the cathode terminal l. A similar but smaller section 19 at the lower end of the tube is sealed along one edge to a ilange 2| on the lower grid terminal in and along the other edge to a flange 22 on the cathode terminal 8. The cathode terminals are joined by a glass ring 23 sealed to flanges 2t and 288 on the terminals.

This completes the envelope and provides exposed surfaces on the several terminals externally of the envelope. As clearly seen in Figure l, the envelope side walls, the three electrodes and the various electrode terminals are all coaxial with the envelope axis 21.

The ring-shaped grid 4 lies as a cylinder between cathode 6 and anode 3 and is supported by metal end rings 28 and 36 projecting from the grid terminals 5 and I0 respectively. The grid may be of any suitable openwork structure such as vertical bars extending between the end rings.

This preferred double-ended grid terminal arrangement has the advantage of being able to make circuit connections at either or both ends of the tube, and the additional advantage of providing support for both ends of the grid.

The ring-shaped cathode 6 lies as a cylinder inside the grid. In the tube illustrated in Figure 1, a filamentary type of cathode is used, comprising a series of parallel thoriated tungsten wires. These wires are supported at the ends by circular supports 29 projecting radially from mounting rings 3i fastened to the cathode terminals 1 and 3. By this arrangement a multiplicity of filament wires are provided, whereby a large cathode area is presented to the anode of the tube. Such large electron emitter surface is im- 3 portant in high power tubes. In order to improve the thermal efiiciency of the cathode, a cylindrical heat shield 32 is located back of the filaments, which shield is conveniently supported from the mounting ring 3! by a flange 33.

My improved tube has many advantages. The desired large cathode area is provided in a structure embodying fairly short electrodes. This shortness of electrode length is very important, particularly in high frequency tubes. For example, much closer grid-to-cathode spacings can be.

established and maintained than would be possible ii long electrodes were used. Also, the compact coaxial electrodes in combination with the coaxial terminal arrangement provides short, low inductance connections between the electrodes and associated circuits. As already mentioned, the annular tube with its coaxial terminals is well adapted for use with linear circuits.

Another advantage lies in cooling the tube. One of the major problems in high power tubes "isthe one of heat dissipation. With my improved annular envelope both the inside and outside walls are -exposed for removing heat "from the electrodes, in fact, the entire central part of the envelobe is open to form an air passage. Cooling air may thus be directed along both the inner and outer side walls'of the tube. Radial cooling fins 3 1 retained by a sleeve 35 are preferably provided on a'no'de 3. This cooler also provides a convehient terminal for i'rl'aking circuit connection to the anode. I

Figure 2 shows a modified tube'i n which only one grid terminal is employed. Here the upper "end of the tube is similar to that shown in Figure 1, while the lower end has a single annular U- shaped section 35 sealed]along one edge to the alf'i'ode flange l3 and along the other edge to the cathode terminal flan e This view also illustrates the use of an indirectly heated cathode comprising a, cathode sleeve 3? connected to a support Stand heated by filamen't wires 39 located inside the sleeve, which heater filaments are connected between thesuppor't 38 and a second support ll so that the-filaments are connected across the cathode terminals. The cathode sleeve may be ooate d or treated with any suitable electron emissive material.

1. An'electron tube 'comprisingan annular envelope having generally cylindrical inner and outer walls, a plurality of ring-shaped electrodes including an anode and grid and cathode, said anode forming part of one of said walls, manne- "sh'aped terminals on the envelope for the grid and cathode, said walls and electrodes and terminals being concentric with the tube axis. I

'2. An electron tube comprising an annular envelope having generally cylindrical inner and outer Walls, "a plurality of ring sha'ped electrodes including an anode and grid and cathode, said anode forming part of one of said walls, and ring-shaped terminals on the envelope for the grid and cathodaone of said terminals forming part of the other of said Walls, said walls and electrodes and terminals being concentric with the tube axis.

3. An electron tube comprising an annular envelope having generally cylindrical inner and outer walls, a plurality of ring-shaped electrodes including an anode and grid and cathode, said anode forming part of one of said walls, and ringshaped terminals on the envelope for the grid and cathode, the cathode terminal forming part of the other of said walls and the grid terminal being located between the walls at one end of the envelope, said walls and electrodes and terminals being concentric with the tube axis.

4. An electron tube comprising an annular envelope having generally cylindrical inner and outer Walls, a plurality of ring-shaped electrodes including an anode and grid and cathode, said anode forming part of one of said walls, a ringshaped terminal on the envelope for the cathode, and a pair of aligned ring-shaped terminals on the envelope for the grid, the cathode terminal forming part of the other of said walls and the grid terminals being located between the walls at opposite ends of the envelope, said walls and electrodes and terminals being concentric with the tube axis.

5. An electron tube comprising an annular envelope having generally cylindrical inner and masseu e plurality of ring-shaped electrodes including an anode and grid and cathode, said anode forming part of the outer wall, and ringshaped terminals on the enyelope for the cathode 'ahd'grid, one or said te'rinitials forming part of the inner wall, Said walls and electrodes and ter 'r'ni'nal's being concentric the tube axis.

6. An electron tube comprising an annular envelope having generals cylindrical inner and outer walls, a et rnity or ring-shaped electrodes ih'cluding an anode and cathode, said anode forming part of one of said Walls, a pair of ring-shaped cathode terminals on the'envelbpe, said cathode terminals formihe pan of the other or said 'walls, ah'd'radi'ally extending conductor means connecting the cathode with said tel: na ls'said walls and electrodes and "terminals being concentric with thetub'e axis. v

7. An electron tube comprising an annular envelope having generally cylindrical inner and outerwans, a pluralitybf neg-shaped electrodes including an anode and cathode, said anode forming part of one of said walls, a pair of ring-shaped cathode terh'iih'als ont h'e envelope, said cathode terminals forming part oruie other of 'said 'walls, the cathode comprising agents of "parallel hiai'ri'en't's, and a pair of stated "susports'pro'jectmg radially from said terminals aha connected to the ends of the ma nts, ald wane and electrodes and terminals sifig'ctnee'iitn'e with the tube axis. 8. An electron t be ttmpnsmg' an answer envelope having generally cylindrical inner and outer walls, a plurality of neg-shaped electrodes including anode anacsthsoeaaid ahode formmg part of one of said walls, and a cylindrical heat shield interposed between the cathode and the othelf o'f said. Walls, 5 d wens and electrodes and shield being "concen'triewi'th the tube axis. CLAYTON E. MURDOCK.

7 REFERENCES 'oliti z n fhe following references are of record in the file of this patent:

UNITED STATES PATENTS- Numbe'r g Name Date 1,196,417; Nicolson Aug. 29,1"916 2,121,690 Knowles 'et a1 June 21, 1'93}; 2,216,170 eorge Oct. 1, 1'940 2,407,274. Hartley 'et 8,1 se'pt. To, 1946 2,436,549 Kane Feb. 24, 1948 2455;846 West Dec. '1, I948 

